Many modern aircraft components are made of composite material. Forming of the composite material into a desired aircraft component may be achieved using a variety of composite manufacturing techniques, such as hand lay-up, drape forming, press forming, and automatic fiber placement (AFP). These methods may all be prone to strain and wrinkling of the composite material when forming parts having extreme curvature or complex curvatures and have various other disadvantages, as described below.
Hand lay-up is a labor intensive process and requires single ply application of multiple layers of composite material to a formed surface to form a part. Hand lay-up also involves several vacuum compaction cycles to remove trapped air and consolidate composite plies. These vacuum compaction cycles require expensive consumable materials, such as elastomeric vacuum bags, which must be discarded after the part is completed.
Drape forming or hot drape forming is a process using a vacuum chamber defined by an elastomeric material sealed around uncured composite material placed on a single form block. The uncured composite material is then heated before atmosphere is evacuated from the vacuum chamber. This causes external atmosphere to push against the elastomeric material, thereby pressing the composite material against the form block. However, this process is limited to forming only one or two flanges in the same direction simultaneously and straight or slightly-curved parts.
Press forming is a process using heavy and expensive equipment to form flanges of a composite part. Press forming generally requires two form dies, one acting as a base for the material to form to and the other die acting as a pusher. However, like drape forming, press forming is generally limited to forming only one or two flanges in the same direction simultaneously and straight or slightly-curved parts.
AFP is a process using heavy and expensive equipment to place multiple layers of individual strips of uncured composite material, such as prepreg tow, onto a form block or shape. This process is time consuming and is generally limited to forming only one or two flanges in the same direction.